Indexed tri-planar osteotomy guide and method

ABSTRACT

Methods and devices for performing an osteotomy produce a bone cut producing a multi-planar change in the alignment of a bone portion by rotating it relative to another bone portion.

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/047,666 filed Feb. 19, 2016, entitled “Indexed Tri-Planar OsteotomyGuide and Method”, which claims the benefit of U.S. ProvisionalApplication No. 62/118,378, filed Feb. 19, 2015, entitled “IndexedTri-Planar Osteotomy Guide and Method”. The foregoing is incorporatedherein by reference in their entirety.

FIELD OF THE INVENTION

The invention relates to methods, implants, and instruments forperforming an osteotomy.

BACKGROUND

Various conditions may affect skeletal joints such as the deterioration,elongation, shortening, or rupture of soft tissues, cartilage, and/orbone associated with the joint and consequent laxity, pain, and/ordeformity. It is often desirable to change the angular alignment of abone or a portion of a bone to restore function and/or reduce pain. Tothis end, various osteotomy procedures and instruments have beenproposed. For example, osteotomies have been performed throughout thebody to make various angular adjustments such as in a tibia, fibula,femur, pelvis, humerus, ulna, radius, metacarpal, metatarsal, and otherbones.

SUMMARY

The present invention provides methods, implants, and instruments forperforming an osteotomy.

In one example of the invention, methods and devices for performing anosteotomy produce a bone cut allowing multi-planar correction of thealignment of a bone portion by rotating it relative to another boneportion.

In another example of the invention, an osteotomy system operable toguide the formation of a tri-planar rotational osteotomy between aproximal portion of a metatarsal bone and a distal portion of themetatarsal bone, includes at least one cutter guide and a cutter. Thecutter guide includes reference features operable to align the cutterguide with the metatarsal bone in a predetermined position and one ormore cutter guiding features each defining an osteotomy plane orrotation axis relative to the metatarsal bone and corresponding to acoupled change in at least two of intermetatarsal angle, pronation, andplantar flexion of the distal portion of the metatarsal bone, at leastone of the change in intermetatarsal angle, pronation, and plantarflexion being user selectable among a plurality of values at the time ofsurgery. The cutter is operable to selectively reference one of the oneor more cutter guiding features to cut the metatarsal bone to mobilizethe proximal portion of the metatarsal bone and the distal portion ofthe metatarsal bone relative to one another and produce cut surfaces onwhich the distal metatarsal bone portion and proximal metatarsal boneportion are relatively rotatable.

In another example of the invention, a method of performing an osteotomyon a metatarsal bone having a proximal portion and a distal portion, theproximal and distal portions defining a first relative position betweenthem, includes determining a desired positional change between theproximal portion of the metatarsal bone and the distal portion of themetatarsal bone in at least two anatomic reference planes; mounting aguide on the metatarsal bone; establishing an osteotomy plane orrotational axis with the guide; guiding a cutter in the osteotomy planeor about the rotational axis to mobilize the proximal portion of themetatarsal bone and the distal portion of the metatarsal bone relativeto one another and produce cut surfaces on which the distal portion ofthe metatarsal bone and proximal portion of the metatarsal bone arerelatively rotatable, the cut surfaces being oriented to incorporate thedesired positional change in the at least two anatomic reference planes;rotating the distal portion of the metatarsal bone relative to theproximal portion of the metatarsal bone to a second relative positiondifferent from the first relative position; and fixing the distalportion of the metatarsal bone and the proximal portion of themetatarsal bone relative to one another in the second relative positionwith the cut surfaces of the proximal portion of the metatarsal bone andthe distal portion of the metatarsal bone abutting one another.

BRIEF DESCRIPTION OF THE DRAWINGS

Various examples of the present invention will be discussed withreference to the appended drawings. These drawings depict onlyillustrative examples of the invention and are not to be consideredlimiting of its scope.

FIG. 1 is medial view of a foot illustrating anatomic reference planesand relative directions;

FIG. 2 is a lateral view of a foot illustrating dorsiflexion and plantarflexion;

FIG. 3 is a coronal view of a foot illustrating inversion and eversion;

FIG. 4 is a dorsal view illustrating bones, tendons, and ligaments ofthe foot;

FIG. 5 is a plantar view illustrating bones, tendons, and ligaments ofthe foot;

FIG. 6 is a perspective view illustrating bones, tendons, and ligamentsof the foot;

FIG. 7 is a medial view of the MTP joint of the first ray of the foot;

FIG. 8 is a sectional view taken along line 8-8 of FIG. 7;

FIG. 9 is a dorsal view of the MTC joint of the first ray of the foot;

FIG. 10 is a medial view of the MTC joint of the first ray of the foot;

FIG. 11 is a dorsal view illustrating deformity of the foot;

FIG. 12 is a plantar view illustrating deformity of the foot;

FIG. 13 is a sectional view similar to that of FIG. 8 but illustratingdeformity of the foot;

FIG. 14 is dorsal view of bones of the first ray of a human footillustrating coordinate axes according to the present invention;

FIG. 15 is a medial view of the bones of FIG. 14 illustrating coordinateaxes according to the present invention;

FIG. 16 is a dorsal view of a metatarsus illustrating coordinate axesaccording to the present invention;

FIG. 17 is a medial view of the metatarsus of FIG. 16 illustratingcoordinate axes according to the present invention;

FIG. 18 is an anterior view of the metatarsus of FIG. 16 illustratingcoordinate axes according to the present invention;

FIGS. 19A-19D are schematic views illustrating the orientation of ametatarsus before and after an osteotomy according to the presentinvention;

FIGS. 20 and 21 are isometric views of a saw blade according to thepresent invention;

FIG. 22 is a side view of the saw blade of FIGS. 20 and 21;

FIG. 23 is an isometric view of a cut block according to the presentinvention;

FIGS. 24-28 are orthographic views of the cut block of FIG. 23;

FIGS. 29-34 are orthographic views of a cut guide according to thepresent invention;

FIG. 35 is an isometric view of an axis guide according to the presentinvention;

FIGS. 36-41 are orthographic views of the axis guide of FIG. 35;

FIGS. 42-54 illustrate a method of performing an osteotomy on a boneaccording to the present invention;

FIG. 55 is an isometric view of a cut guide according to the presentinvention;

FIG. 56 is another isometric view of the cut guide of FIG. 55;

FIGS. 57-61 are orthographic views of the cut guide of FIG. 55;

FIG. 62 is a top plan, or dorsal, view of a set of cut guides includingthe cut guide of FIG. 55 and additional similar guides having varyingsizes and orientation; and

FIGS. 63-65 illustrate a method of performing an osteotomy on a boneaccording to the present invention utilizing one of the cut guides ofFIG. 62.

DESCRIPTION OF THE ILLUSTRATIVE EXAMPLES

The following illustrative examples describe implants, instruments andtechniques for performing an osteotomy. The present invention may beused to perform osteotomies on any bone including but not limited to atibia, fibula, femur, pelvis, humerus, ulna, radius, metacarpal, andmetatarsal.

While instruments and techniques according to the present invention maybe used in conjunction with any bone or joint, the illustrative examplesare shown in a size and form most suitable for the joints of the handand foot. The hand and foot have a similar structure. Each has a volaraspect. In the hand the volar, or palmar, aspect includes the palm ofthe hand and is the gripping side of the hand. In the foot the volar, orplantar, aspect is the sole of the foot and is the ground contactingsurface during normal walking. Both the hand and foot have a dorsalaspect opposite the volar aspect. Both the hand and foot include longbones generically described as metapodial bones. In the hand, themetapodial bones are referred to as metacarpal bones. In the foot, themetapodial bones are referred to as metatarsal bones. Both the hand andfoot include a plurality of phalanges that are the bones of the digits,i.e. the fingers and toes. In both the hand and foot, each of the mostproximal phalanges forms a joint with a corresponding metapodial bone.For convenience, the invention will be illustrated with reference to ametatarsus of the first ray of a human foot.

FIG. 1 illustrates the orientation of anatomic planes and relativedirectional terms that are used for reference in this application. Thecoronal plane 10 extends from medial 12 (toward the midline of the body)to lateral (away from the midline of the body) and from dorsal 14(toward the top of the foot) to plantar 16 (toward the sole of thefoot). The sagittal plane 18 extends from anterior 20 (toward the frontof the body) to posterior 22 (toward the back of the body) and fromdorsal 14 to plantar 16. The transverse plane 24 extends anterior 20 toposterior 22 and medial to lateral parallel to the floor 26. Relativepositions are also described as being proximal or distal where proximalis along the lower extremity toward the knee and distal is along thelower extremity toward the toes. The following examples serve todemonstrate the relative directions. The great toe is medial of thelesser toes and the fifth toe is lateral of the great toe. The toes aredistal to the heel and the ankle is proximal to the toes. The instep isdorsal and the arch is plantar. The toenails are dorsal and distal onthe toes.

FIG. 2 illustrates dorsiflexion 23 in which the toes are moved dorsally,or closer to the shin, by decreasing the angle between the dorsum of thefoot and the leg and plantar flexion 25 in which the toes are movedplantar, or further away from the shin, by increasing the angle betweenthe dorsum of the foot and the leg. For example when one walks on theirheels, the ankle is dorsiflexed and when one walks on their toes, theankle is plantar flexed.

FIG. 3 illustrates inversion 27 in which the sole of the foot is tiltedtoward the sagittal plane or midline of the body and eversion 29 inwhich the sole of the foot is tilted away from the sagittal plane.

FIGS. 4-10 illustrate the arrangement of the bones within the foot 30. Aright foot is illustrated. Beginning at the proximal aspect of the foot,the heel bone or calcaneus 32 projects plantar. The talus 34 is dorsalto the calcaneus 32 and articulates with it at the talocalcaneal orsubtalar joint. Dorsally, the talus articulates medially with the tibia36 and laterally with the fibula 38 at the ankle joint. Distal to theankle are the navicular bone 40 medially and the cuboid bone 42laterally which articulate with the talus and calcaneus respectively.The navicular bone 40 and cuboid bone 42 may also articulate with oneanother at the lateral side of the navicular bone and the medial side ofthe cuboid bone. Three cuneiform bones lie distal to the navicular boneand articulate with the navicular bone and one another. The first, ormedial, cuneiform 44 is located on the medial side of the foot 30. Thesecond, or intermediate, cuneiform 46 is located lateral of the firstcuneiform 44. The third, or lateral, cuneiform 48 is located lateral ofthe second cuneiform 46. The third cuneiform 48 also articulates withthe cuboid bone 42. Five metatarsals 50, 52, 54, 56, 58 extend distallyfrom and articulate with the cuneiform and cuboid bones. The metatarsalsare numbered from 1 to 5 starting with the first metatarsal 50 on themedial side of the foot and ending with the fifth metatarsal 58 on thelateral side of the foot 30. The first metatarsal 50 articulates withthe first cuneiform 44 at a metatarsocuneiform (MTC) joint 51. Thesecond metatarsal 52 articulates with the first, second and thirdcuneiforms 44, 46, 48 and may articulate with the first metatarsal aswell. Five proximal phalanges 60, 62, 64, 66, 68 extend distally fromand articulate with the five metatarsals respectively. The firstproximal phalanx 60 articulates with the first metatarsal 50 at ametatarsophalangeal (MTP) joint 61. One or more distal phalanges 70, 72,74, 76, 78 extend distally from the proximal phalanges. The firstmetatarsal 50, first proximal phalanx 60, and, first distal phalanx 70together are referred to as the first ray of the foot. Similarly, themetatarsal, proximal phalanx, and distal phalanges corresponding to thelesser digits are referred to as the second through fifth raysrespectively.

FIG. 4 is a dorsal view illustrating bones, tendons and ligaments of thefoot. Plantar structures illustrated in FIG. 5 are omitted from FIG. 4for clarity. The extensor hallucis longus muscle originates in theanterior portion of the leg, the extensor hallucis longus tendon 80extends distally across the ankle and along the first ray to insert intothe base of the distal phalanx 70. The tibialis anterior muscleoriginates in the lateral portion of the leg and the tibialis anteriortendon 82 extends distally across the ankle and inserts into the firstcuneiform 44 and first metatarsus 50 at the first MTC joint 51 where itcontributes to the MTC capsular structure 84 (FIGS. 9 and 10). Atransverse intermetatarsal ligament 83 inserts into the capsule of theMTP joint such that it connects the heads of the first through fifthmetatarsal bones. In FIGS. 4 and 5, only the connection between thefirst and second metatarsal bones 50, 52 is shown.

FIG. 5 is a plantar view illustrating bones, tendons, and ligaments ofthe foot. Dorsal structures shown in FIG. 4 are omitted from FIG. 5 forclarity. The peroneus longus muscle originates at the head of the fibulaand its tendon 86 passes posteriorly around the lateral malleolus 88 ofthe ankle, around the cuboid notch 90 on the lateral side of the cuboidbone 42, along the peroneal sulcus 92 on the plantar surface of thecuboid bone 42, and inserts into the first metatarsal 50. The flexorhallucis brevis muscle 94 originates from the cuboid 42 and thirdcuneiform 48 and divides distally where it inserts into the base of theproximal phalanx 60. Medial and lateral sesamoid bones 96, 98 arepresent in each portion of the divided tendon at the MTP joint 61. Thesesamoids 96, 98 articulate with the plantar surface of the metatarsalhead in two grooves 100, 102 separated by a rounded ridge, or crista 104(FIG. 8). The flexor hallucis longus muscle originates from theposterior portion of the fibula 38. The flexor hallucis longus tendon106 crosses the posterior surface of the lower end of the tibia, theposterior surface of the talus, runs forward between the two heads ofthe flexor hallucis brevis 94, and is inserted into the base of thedistal phalanx 70 of the great toe.

FIG. 7 is a medial view of tendons at the MTP joint 61 of the first ray.A medial collateral ligament 108 originates from the head of the firstmetatarsus 50 and inserts into the proximal phalanx 60. A medialmetatarsosesamoid ligament 110 originates from the head of the firstmetatarsus 50 and inserts into the medial sesamoid bone 96. Similarcollateral and metatarsosesamoid ligaments are found on the lateral sideof the first MTP joint. The flexor hallucis brevis 94 is shown insertinginto the sesamoids 96, 98. Ligamentous fibers extend further distally inthe form of a phalangealsesamoid ligament 112 from the sesamoids to theproximal phalanx 60.

FIG. 8 is a sectional view taken along line 8-8 of FIG. 7 showing themetatarsal head 50, the tendon of the extensor hallucis longus 80, themedial and lateral sesamoid bones 96, 98, the grooves 100, 102 in whichthe sesamoids articulate, the crista 104 separating the grooves, theflexor hallucis longus 106, the abductor hallucis 114, and the adductorhallucis 116.

FIG. 9 is a dorsal view showing the dorsal capsular structure 84 of theMTC joint 51 of the first ray including the insertion of the tibialisanterior tendon 82.

FIG. 10 is a medial view of the MTC joint 51 of the first ray showingthe medial capsular structure 118 including the insertion of thetibialis anterior tendon 82.

FIGS. 11-13 illustrate deformities of the first ray. In a dorsal view,as shown in FIG. 11, an intermetatarsal angle (IMA) 120 may be measuredbetween the longitudinal axes of the first and second metatarsal bones50, 52. The angle is considered abnormal when it is 9 degrees or greaterand the condition is known as metatarsus primus varus (MPV) deformity. Amild deformity is less than 12 degrees, a moderate deformity is 12-15degrees, and a severe deformity is greater than 15 degrees. Similarly, ahallux valgus angle (HVA) 122 may be measured between the longitudinalaxes of the first metatarsus 50 and the first proximal phalanx 60 at theMTP joint 61. The angle is considered abnormal when it is 15 degrees orgreater and the condition is known as a hallux valgus (HV) deformity. Amild deformity is less than 20 degrees, a moderate deformity is 20 to 40degrees, and a severe deformity is greater than 40 degrees.

MPV and HVA often occur together as shown in FIGS. 11-12. As thedeformities progress several changes may occur in and around the MTC andMTP joints. Referring to FIG. 13, as the IMA and HVA increase, theextensors 80, flexors 106, abductors 114, and adductors 116 of the firstray (along with the sesamoids 96, 98) are shifted laterally relative tothe MTP joint. The tendons exert tension lateral to the MTP jointcreating a bow string effect (as best seen in FIGS. 11 and 12) thattends to cause the deformities to increase. The relative shift of thesesamoids 96, 98 is often accompanied by erosion of the crista 104. Theabnormal muscle forces cause the metatarsus 50 to pronate, or in otherwords, rotate so that the dorsal aspect of the bone moves medially andthe plantar aspect moves laterally. Rotation in the opposite directionis referred to as supination. Soft tissues on the medial side of the MTPjoint and lateral side of the MTC joint attenuate, through lengtheningand thinning, thus weakening the capsule and permitting the deformitiesto progress. Soft tissues on the opposite sides of the capsule tend toshorten, thicken and form contractures making it difficult to reduce thejoints to their normal angular alignment.

More generally, deformities of the first ray may include metatarsusprimus varus, hallux valgus, abnormal pronation, abnormal supination,abnormal dorsiflexion, and/or abnormal plantar flexion. Thesedeformities correspond to three different planar rotations. Metatarsusprimus varus and hallux valgus result from rotations in the transverseplane 24. Pronation and supination are rotation in the coronal plane 10.Dorsiflexion and plantar flexion are rotation in the sagittal plane.

The terms “suture” and “suture strand” are used herein to mean anystrand or flexible member, natural or synthetic, able to be passedthrough material and useful in a surgical procedure. The term“transverse” is used herein to mean crossing as in non-parallel.

The present invention provides methods and devices for performing anosteotomy. In a method according to the present invention, a desiredpositional change between two bone portions is predetermined and thenthe bone is cut to allow the bone portions to be repositioned in the newposition. By way of illustrative example, FIGS. 14 and 15 illustrate themedial cuneiform 200, first metatarsus 202, and proximal phalanx 204 ofthe first ray of a human foot with overlying coordinate axes. FIG. 14 isa dorsal view, looking down, on the first ray. FIG. 15 is a medial view,looking from the medial side, of the first ray. The Z-axis is positiveplantar, the X-axis is positive medial, and the Y-axis is positivedistal. The Y-axis is parallel to the anatomic axis of the firstmetatarsus. The Y-Z plane is a local, first metatarsal sagittal planeand in a healthy foot is rotated slightly medial about the Z-axisrelative to the sagittal plane of the body. The X-Y plane is a local,first metatarsal transverse plane and in a healthy foot is rotatedslightly dorsal about the X-axis relative to the transverse plane of thebody due to the natural angle of the foot. The X-Z plane is a local,first metatarsal coronal plane and in a healthy foot is rotated slightlyanterior about the X-axis relative to the coronal plane of the body dueto the natural angle of the foot.

FIGS. 16-18 illustrate the metatarsus 202 alone with the coordinate axesof FIGS. 14 and 15. Rotation about each of the axes is shown. Referringto FIG. 16, rotation in the X-Y plane about the Z-axis results in achange in the IMA. Referring to FIG. 17, rotation in the Y-Z plane aboutthe X-axis results in a change in dorsiflexion/plantarflexion. Referringto FIG. 18, rotation in the X-Z plane about the Y-axis results in achange in pronation/supination. In the case of an osteotomy, a cut ismade in a bone to change the position of one portion of the bonerelative to another portion. For example, in a metatarsus 202, it may bedesirable to change the position of the distal metatarsal head 206relative to the proximal portion of the bone. As shown in FIG. 16, acylindrical cut 208, also referred to as a crescentic cut, concentricwith the Z-axis allows a change in IMA by rotating the cut surfacesrelative to one another about the Z-axis Likewise, as shown in FIG. 17,a cylindrical cut 210 concentric with the X-axis allows a change inflexion angle by rotating the cut surfaces relative to one another aboutthe X-axis. Similarly, a planar cut 212 parallel to the X-Z plane (FIGS.16 and 17) allows a change in pronation/supination by rotating the cutsurfaces about the Y-axis (FIG. 18).

It is possible to create an oblique cut, i.e. a cut angled relative totwo or three axes, that results in simultaneous angular changes in 2 or3 anatomic planes. For example, referring to FIG. 19A, an initialposition 214 of a bone portion axis can be changed by rotating the boneportion about two axes to a new position 216. Using the illustrativeexample of FIGS. 14-18, this would correspond to plantar flexing themetatarsus by an angular amount 218 corresponding to a plantardisplacement 220 of the distal head 206 and decreasing the IMA anangular amount 222 corresponding to a lateral displacement 224 of thedistal head 206. These two motions to move to the new position 216 canbe resolved to a bi-planar rotation plane 226 having a bi-planarrotation axis 228 normal to the bi-planar rotation plane 226. In otherwords, cutting the bone and relatively rotating the resulting boneportions in the bi-planar rotation plane 226, e.g. such as about thebi-planar rotation axis 228, will simultaneously change the relativeplantar flexion and IMA of the bone portions. For any given combinationof predetermined plantar displacement 220 and change in IMA 222,rotating the cut bone portions to achieve one of the changes willnecessarily produce the other change due to the coupled motion about thebi-planar rotation axis 228. For example, repositioning the boneportions to reduce the IMA by the predetermined amount 222 will alsoresult in the predetermined plantar displacement 220. For manycombinations of correction, the bone cut may be a crescentic cut coaxialwith the bi-planar rotation axis 228 or a planar cut normal to thebi-planar rotation axis 228. For other combinations, the angle of thebi-planar rotation axis 228 may make either a crescentic cut or a planarcut more practical.

Referring to FIGS. 19A and 19B, an additional rotation about the boneaxis from the initial position 214 to the new position 216 may beincluded and when combined with the other two motions results in atri-planar rotation axis 230 about which a rotation will result in atri-planar correction. In the illustrative example of FIGS. 14-18, thisadditional rotation corresponds to a change in pronation/supination ofthe metatarsus about its anatomic axis. In FIG. 19B, a first plane maybe constructed containing the bi-planar rotation axis 228 and theinitial position 214 of the bone portion axis. A second plane may beconstructed containing the bi-planar rotation axis 228 and the newposition 216 of the bone portion axis. A bisector plane 215 contains thebi-planar rotation axis 228, the tri-planar rotation axis 230 and isangularly spaced half-way between the initial and new positions 214,216.

FIG. 19C illustrates the motion of the end of the metatarsus 202 in amotion plane 217 (FIG. 19B) perpendicular to the bisector plane 215 forthe case of rotation about the bi-planar rotation axis 228. A referencemark 219 is included to illustrate the pronation/supination of the bone.With rotation about the bi-planar rotation axis 228, the end of themetatarsus translates from the initial position 214 to the new position216 resulting in a medial/lateral displacement 221 and a dorsal/plantardisplacement 223 but without any change in pronation/supination; i.e.without any rotation about the anatomic longitudinal axis.

FIG. 19D illustrates the motion of the end of the metatarsus 202 in themotion plane 217 for the case of rotation about the tri-planar rotationaxis 230. With rotation about the tri-planar rotation axis 230, the endof the metatarsus translates medial/lateral 221, translatesdorsal/plantar 223 and rotates 225 in pronation/supination from theinitial position 214 to the new position 216.

Referring to FIG. 19B, the bi-planar rotation axis 228 lies in the X-Zplane at an angle θ 227 relative to the Z-axis. The tri-planar rotationaxis 230 lies in the bisector plane 215 at an angle Φ 229 from thebi-planar rotation axis 228. Letting α=the change in IMA 222, ω=thechange in pronation/supination 225, L=the metatarsal axis length fromthe rotation axis to the joint line of the MTP joint, C=thedorsal/plantar displacement 220 of the metatarsal head, and R=the ratioC/L, then θ=fn(R, α) and Φ=fn(α, ω) using vector transformations as isknown in the art.

By determining the current position of an abnormally positionedmetatarsus and the desired final position, a desired positional changein each plane may be determined. The current and desired positions maybe determined by medical imaging, computer modeling, manual measurement,or other techniques as is known in the art. The desired positionalchange may be expressed as an angular change or, for a given positionrelative to the osteotomy location, it may be expressed as adisplacement. For example, in the illustrative example of an osteotomyof the first metatarsus, it may be desirable to express one or more ofthe positional changes in terms of a displacement of the distalmetatarsal head 206 such as, e.g., the plantar displacement 220 of FIG.19A. As long as the distance from the metatarsal head to the rotationaxis of the osteotomy is known, the positional change may be expressedas either an angle or a displacement. In the following examples, forexample, plantar flexion is expressed as an amount of plantardisplacement of the distal head of the metatarsus, based either a gaugedmetatarsal axis length L or an estimated metatarsal axis length Ldetermined as the difference between an average metatarsus overalllength and a gauged distance from the proximal end of the metatarsus tothe osteotomy.

An illustrative method according to the present invention produces anosteotomy between a first bone portion and a second bone portion. Thebone portions define a first relative position between them. The methodincludes defining a rotation axis or a corresponding rotation plane infixed relationship to the bone, referencing a cutter to the rotationalaxis or plane, cutting the bone to mobilize the first and second boneportions relative to one another, and rotating the first bone portionrelative to the second bone portion within the rotation plane and/orabout the rotational axis. The rotational axis and plane incorporate adesired positional change in one or more planes, preferably in two orthree anatomic planes. For example, to reposition a first portion of abone relative to a second portion of the bone, an axis guide may beprovided that defines one or more rotational axes. Each rotational axismay incorporate an angular change in one or more anatomic referenceplanes. Each rotational axis may be incorporated into the axis guide by,e.g., calculating angles θ 227 and Φ 229 as described above for aparticular combination of corrections. The axis guide may then bemodeled along with features operable to orient the guide relative toanatomic reference planes. Each rotational axis may then be superimposedon the model relative to the same anatomic reference planes and be usedto define a feature such as a hole, pin, slot, groove, intersectingsurfaces, or other suitable features corresponding to the rotationalaxis or corresponding rotational plane. A cutter may be referenced toone of the rotation axes or rotational planes and guided to mobilize thefirst and second bone portions relative to one another. The boneportions may then be relatively rotated within the rotational planeand/or about the rotation axis, to realize the angular change in the oneor more reference planes. In one example, the cutter may be linkeddirectly to the axis guide. In another example, the axis guide may beused to provide a feature such as a hole or pin in the bone defining therotation axis which is referenced by the cutter. The axis guide may beremoved prior to referencing the cutter to the rotation axis. Forexample, the axis guide may include a guide hole corresponding to eachrotation axis and the guide hole may be used to place a pin in the bonealigned with a desired rotation axis and the axis guide may then beremoved. A cutter may then engage the pin for rotation about the pin tocreate a cylindrical cut in the bone about which the bone portions maybe relatively rotated. Alternatively, a cut guide defining a cut planemay be referenced to the pin. A cutter may then be guided in the cutplane to create a planar cut between the bone portions. The boneportions may then be rotated about the rotation axis. Alternatively, acut guide defining one or more rotation planes corresponding to one ormore predetermined multi-planar corrections may be provided. The cutguide may be referenced to the bone and used to guide a cutter to createa planar cut between the bone portions without first creating a rotationaxis in or on the bone. In this case, the rotation plane or planescorresponding to the rotation axes are defined by the guide and theguide is positioned on the bone by aligning reference features of theguide with the bone to orient the guide to correctly position the one ormore rotation planes. The guide may then be used to guide a cutterdirectly to create a planar cut in the bone corresponding the to thedesired rotation plane. The freed bone portions may then be rotated inthe rotation plane to achieve the multi-planar correction.

FIGS. 20-22 depict an illustrative crescentic blade 250. The blade 250has a thin wall 252 forming a portion of a cylinder curved about a bladeaxis 254 and extending from a proximal end 256 to a distal end 258.Teeth 260 are formed on the distal end 258. The proximal end 256 isattached to a shaft 262 coaxial with the blade axis 254. The shaft 262may be attached to a powered handpiece to rotate the blade about theblade axis and form a cylindrical cut in a bone. By using an oscillatingmotion, a cut transcribing an arc of a cylinder can be made. The shaft262 may include an axial bore 264 coaxial with the blade axis 254 ableto receive a pin in rotational engagement for guiding the blade inrotation about the pin.

FIGS. 23-28 depict an illustrative cut block 270. The cut block 270 hasa bore 272 defining a rotation axis 274. The bore 272 is able to receivea pin in axial sliding and rotational relationship. The cut blockincludes a curved surface 276 defining at least a portion of a cylinderparallel to the rotation axis 274. The cut block 270 may be pinned to abone by placing a pin through the bore 272 and into the bone. A secondpin may be placed through a second bore 278 and into the bone to preventthe cut block from rotating about the first pin. A cutter, such as thecrescentic blade 250 of FIGS. 20-22, may be guided to form a cut aboutthe rotation axis 274 of the cut block by pressing the curved bladeagainst the curved surface 276.

FIGS. 29-34 depict an illustrative blade guide 280. The blade guide 280includes a shaft 282 having a bore 284 defining an axis 286 extendingbetween a proximal end 288 and a distal end 290. A set screw 291 iscontained in a hole transverse to the bore 284. The set screw 291 may betightened to lock the blade guide 280 to a pin received in the bore 284.The blade guide 280 defines a plane 281, normal to the bore axis 286,for guiding a cutter, e.g. a saw blade, to make a planar cut in a bone.In the illustrative example of FIGS. 29-34, a surface 292 formed nearthe distal end 290 defines the plane. More particularly in theillustrative example of FIGS. 29-34, a pair of opposing surfaces definesa slot 294 between them able to receive a saw blade and constrain it tomotion in a plane. The blade guide 280 is narrow proximally and widedistally to provide clearance for soft tissues while providing a wideslot 294 allowing the blade to be swept from side to side within theslot 294. The distal end 290 is offset 296 from the axis 286 so that thebore 284 can be placed on a pin in a bone and the distal end 290 beplaced beside the bone. The distal end 290 is curved as seen in FIGS. 29and 34 to accommodate the particular anatomy of the illustrative examplefor use on a metatarsus of a human foot.

FIGS. 35-41 depict an illustrative axis guide 310. The axis guide 310 isused to establish a rotation axis on a bone for guiding an osteotomycut. The axis guide 310 includes at least one guide hole able to definea rotation axis on a bone. For example, the guide hole may be referenceddirectly. Alternatively, it may be used to guide a drill to form a holein a bone such that the hole may be referenced to guide a cutter.Similarly, the guide hole may guide the placement of a pin that may bereferenced to guide a cutter. When the guide is aligned with a bone, theguide hole defines a rotation axis corresponding to a positional changethat may be produced by an osteotomy in which a cutter is referenced tothe rotation axis. The position change may include changes in one ormore anatomic planes. In the illustrative example of FIGS. 35-41, theaxis guide 310 includes multiple guide holes, each guide hole defining arotational axis corresponding to a different positional change betweenfirst and second bone portions in at least two anatomic referenceplanes. For example, the illustrative axis guide 310 of FIGS. 35-41 isconfigured for establishing rotational axes for a metatarsal osteotomyto produce a positional change in IMA, pronation, and plantar flexion.In the illustrative example of FIGS. 35-41, the plantar flexion isexpressed on the guide as a change in plantar displacement of the distalhead of the metatarsus. The axis guide 310 includes rows 312 and columns314 of guide holes in which each guide hole corresponds to a uniquecombination of change in IMA, pronation, and plantarflexion. Indicia maybe provided on the axis guide 310 to indicate the amount of changeproduced in one or more of IMA, pronation, and plantarflexion, usingeach guide hole. In the illustrative example of FIGS. 35-41, the guideholes define axes that are angled relative to one another in at leasttwo rotational degrees of freedom.

In the illustrative example of FIGS. 35-41, the axis guide 310 may beone of a set of axis guides in which each axis guide has a fixedplantarflexion positional change applied to each guide hole. In theillustrative example of FIGS. 35-41, the particular axis guide 310 showncorresponds to a fixed plantarflexion positional change corresponding to2.5 mm of plantar displacement of the distal head of the metatarsus fora rotational axis a predetermined distance from the distal head of themetatarsus. The setting of that predetermined distance is shown later inthis disclosure. The positional change is expressed in terms of plantardisplacement for convenience. For metatarsal osteotomies, a surgeontypically is interested in preserving the plantar position of the distalhead of the metatarsus or offsetting it a fixed amount. Therefore, it isconvenient to have guides with a fixed plantar change and variable IMAand pronation changes.

For the illustrative axis guide 310 of FIGS. 35-41, the guide hole 316in the row labeled 0 degrees of pronation and the column labeled 15degrees of IMA will establish a rotational axis to guide an osteotomythat when rotated to decrease the IMA by 15 degrees will also result in0 degrees of pronation correction and a 2.5 mm plantar shift of thedistal head of the metatarsus. Similarly, the guide hole 318 in the rowlabeled 5 degrees of pronation and 10 degrees of IMA will establish arotational axis to guide an osteotomy that when reduced to decrease theIMA by 10 degrees will also result in 5 degrees of pronation correctionand a 2.5 mm plantar shift of the distal head of the metatarsus. Axisguides may be provided that incorporate IMA changes corresponding to anyclinically expedient amount, e.g., with the goal of reducing the IMA tofall within a normal anatomic range. Preferably axis guides are providedthat incorporate an IMA reduction ranging from 0 to 25 degrees; morepreferably from 5 to 15 degrees. The guides may incorporate pronationcorrection corresponding to any clinically expedient amount, e.g., withthe goal of correcting pronation to fall within a normal anatomic range.Preferably axis guides are provided that incorporate a pronationcorrection ranging from 0 to 15 degrees; more preferably from 0 to 10degrees. The guides may incorporate plantarflexion changes correspondingto any clinically expedient amount. Preferably axis guides are providedthat incorporate a plantar shift ranging from 0 to 5 mm; more preferably0 to 2.5 mm.

An alignment reference is provided to align the axis guide 310 toanatomic features of the bone so that the positional changes arereferenced to the anatomic planes. An alignment reference may include amark, line, plane, projection, or other suitable reference. In theillustrative example of FIGS. 35-41, a dorsal-plantar through hole 330and a distal hole 332 are provided to receive dorsal and distalalignment rods 334, 336 that are used to align the axis guide 310. Thedorsal-plantar hole 330 may extend through the axis guide 310, as shown,to permit the dorsal alignment rod 334 to be driven through the axisguide 310 and into underlying bone to fix the axis guide 310 to thebone. It is advantageous to offset the holes 330, 332 medial-laterallyas shown in FIGS. 37 and 40 so that the alignment rods 334, 336 do notcollide. The distal alignment rod 336 may include an optional plantardirected pointer 338 at its distal end as an alignment aid. For example,the distal end of the distal alignment rod 336 may be bent to create thepointer 338. The plantar surface 340 of the axis guide 310 is concavemedial-laterally to help stabilize it as it sits on the dorsal surfaceof a bone. An additional fixation hole 342 through the axis guide 310may be used to provide additional fixation of the axis guide 310 to anunderlying bone.

FIGS. 42-54 depict an illustrative method according to the invention. Inthe Illustrative example of FIGS. 42-54, the illustrative instruments ofFIGS. 20-41 are shown in use to perform an osteotomy on a metatarsus ofthe first ray of a human foot for changing the alignment of the firstray.

In FIGS. 42 and 43, the illustrative axis guide 310 of FIGS. 35-41 hasbeen placed on the metatarsus 202. The dorsal alignment rod 334 isaligned with the local sagittal plane of the metatarsus 202. The distalalignment rod 336 is aligned parallel to the metatarsal anatomic axis402. The optional pointer 338 may be aligned with e.g. the joint line ofthe MTP joint to position the axis guide 310 at a predetermined distancefrom the distal head 206. With the axis guide 310 at a predetermineddistance from the distal head 206, angular changes in the position ofthe distal head 206 may optionally be expressed as displacements. Forexample, in the illustrative axis guide 310 of FIGS. 35-41, the changein dorsiflexion is indicated on the axis guide 310 as a plantardisplacement of the metatarsal head. The dorsal alignment rod 334 may bedriven into the metatarsus to temporarily fix the axis guide 310 in thealigned position.

In FIG. 44, an additional pin 344 has been placed through the additionalfixation hole 342 to further stabilize the axis guide 310.

In FIG. 45, an axis pin 346 has been placed through the axis holecorresponding to a 15 degree change in IMA and a 5 degree change inpronation. The particular axis guide 310 also incorporates a 2.5 mmdistal plantar displacement into each of the axis holes.

In FIG. 46, alignment rods 334 and 336, the fixation pin 344, and theaxis guide 310 have been removed leaving just the axis pin 346establishing the rotation axis for a 15 degree IMA, 5 degree pronation,and 2.5 mm distal plantar displacement corrective osteotomy. In theillustrative example of FIG. 46, the cannulated crescentic saw blade 250has been placed over the axis pin 346 and rotated about the rotationalaxis pin 346 to produce a cylindrical cut 347 through the metatarsus202. Alternatively, the cut block 270 may be placed over the rotationalaxis pin 346. The crescentic blade 250 may be guided on the cut block270 alone, without engaging the pin 346, or the blade 250 may engageboth the cut block 270 and the rotational axis pin 346. After the boneis cut, the distal portion is reduced to the desired IMA which willsimultaneously change the pronation angle and plantar position of thedistal bone portion. The bone portions may then be fixed with pins,screws, plates or other suitable fixation elements.

In FIG. 47, as an alternative to using the cannulated crescentic blade250, the blade guide 280 has been placed over the rotational axis pin346 and adjusted to align with a desired cut plane on the metatarsus202. The set screw 291 is tightened to lock the blade guide 280 in placeon the axis pin 346. A saw blade (not shown) is guided in the slot 294to form a planar cut surface through the bone. After the bone is cut,the distal portion is reduced to the desired IMA which willsimultaneously change the pronation angle and plantar position of thedistal bone portion. The bone portions may then be fixed with pins,screws, plates or other suitable fixation elements.

Referring to FIGS. 48 and 49, the rotational axis pin 346 may preferablybe advanced partway into the bone as shown in FIG. 48 prior to cuttingthe bone so that the tip of the pin is dorsal to the slot 294. The bonemay then be cut partially through, including under the rotational axispin 346. The set screw 291 may be loosened and the rotational axis pin346 driven plantar past the planar cut as shown in FIG. 49. The setscrew 291 may be retightened and the remainder of the bone cut through.The bone cut 350 is shown in FIGS. 50 and 51. In this way, therotational axis pin 346 captures the cut bone portions.

FIGS. 52-54 shows the bone with the blade guide 280 removed and therotational axis pin 346 capturing the cut bone portions. The boneportions have been rotated as indicated by arrow 348 about therotational axis pin to the desired IMA (FIG. 52) simultaneously changingthe pronation angle (FIG. 53) and plantar position (FIG. 54) of thedistal bone portion.

FIGS. 55-61 illustrate an alternative cut guide 400. The cut guide maybe used to directly guide a cutter, such as a planar saw blade, tocreate a rotation plane between bone portions corresponding to amulti-planar correction as described relative to the examples above. Thecut guide 400 includes a cutter guiding feature defining a rotationplane and includes reference features that are alignable with a bone toplace the guide in a predetermined orientation relative to the bone. Forsake of clarity, the cutter guiding surface is normal to a rotation axisdetermined as described above. However, in the illustrative example ofFIGS. 55-61, the rotation axis is not discretely defined with a hole orpin but rather the corresponding plane is defined and referenced to thebony anatomy with the reference features.

In the illustrative example of FIGS. 55-61, the guide 400 includes aguide body 402 having a proximal end 404, a distal end 406 opposite theproximal end, a medial side 408, a lateral side 410 opposite the medialside, a top surface 412, and a bottom surface 414 opposite the top. Theguide body 402 includes a fixation feature to temporarily secure theguide body 402 to a bone. The fixation features may include one or moreroughened surface, spike, hole for receiving a pin or screw, strap, orother fixation feature known in the art. In the illustrative example ofFIGS. 55-61, the fixation feature include holes 416, 418 extendingthrough the guide body 402 from the top surface 412 to the bottomsurface 414 and configured to receive a fixation member such as a pin orscrew that extends though the guide body 402 and into the bone.Preferably the holes 416 and 418 are coplanar but not parallel. By beingcoplanar the hole axes define a reference plane that can be used toalign the guide. By being non-parallel, smooth pins inserted through theholes and into an underlying bone will secure the guide body 402 to thebone and prevent it from lifting off of the bone. In the illustrativeexample of FIGS. 55-61, the holes 416, 418 define a plane including aguide body longitudinal axis 420 intersecting the hole axes 422, 424.

The guide body includes reference features for aligning the guide bodywith a metatarsus. In the illustrative example of FIGS. 55-61, thereference features include the bottom surface 414, the proximal end 404,and the longitudinal axis 420 defined by the holes 416, 418.

The guide body 402 includes a plurality of cutter guiding features, eachcorresponding to a different multi-planar correction. The cutter guidingfeatures may be, for example, planar surfaces, slots, or other featuresknown in the art for guiding a cutter to form a planar surface on abone. In the illustrative example of FIGS. 55-61, the cutter guidingfeatures are in the form of saw blade slots 430, 432, 434. Each slot430, 432, 434 is aligned relative to the reference features so that whenbottom surface 414 is resting on the bone, the longitudinal axis 420 isaligned parallel with the metatarsal axis, the hole axes 424, 426 arealigned within the sagittal plane, and the proximal end 404 is alignedwith the MTC joint line, the slot will guide a saw blade to produce arotation plane corresponding to a particular multi-planar correction. Inthe illustrative example of FIGS. 55-61, each slot is configured toproduce 3 degrees of IMA correction and 10, 20, or 30 degrees ofpronation correction. In addition, a slight amount of plantardisplacement of the distal metatarsal head is included in eachcorrection to compensate for shortening of the metatarsus due to thebone removed by the saw blade, i.e. the saw blade kerf. The amount ofplantar displacement is an estimate based on an osteotomy-to-distalmetatarsal head distance determined as the difference between theoverall length of an average human first metatarsus and the distancefrom the MTC joint line to the osteotomy plane. In the illustrativeexample of FIGS. 55-61, the plantar displacement is designed to maintainthe metatarsal head in the same plane it was in prior to the osteotomyto avoid changing the load balance between the five rays of the foot.Typical values of plantar displacement are in the range of 0.1 mm to 3mm. In the illustrative example of FIGS. 55-61, the slots 430, 432, 434define planes that are angled relative to one another in at least tworotational degrees of freedom.

Indicia 436, 438 printed on the guide body 402 indicate the IMAcorrection associated with all of the saw slots on the guide 400 and thedifferent pronation correction associated with each of the saw slots.Additional indicia 440 printed on the guide body 402 indicates that theguide 400 is configured for a right foot.

A handle may be provided to aid in manipulating the guide 400. In theillustrative example of FIGS. 55-61, a handle interface 442 is formed onthe medial side to engage a modular, removable handle (not shown). Thehandle interface may include a slot, tab, dovetail, or other feature asis known in the art for coupling to a modular handle.

FIG. 62 depicts an exemplary kit 450 having a tray 452 for housing theguide 400 of FIG. 55 along with additional guides offering a variety ofconfigurations. In the illustrative example of FIG. 62, a plurality ofguides 400, 454, 456 configured for a right foot is provided on one sideof the tray 452 and a plurality of guides 458, 460, 462 configured for aleft foot is provided on another side of the tray. In the illustrativeexample of FIGS. 55-61, each guide provides for either 3, 6, or 9degrees of IMA correction and the choice of 10, 20, or 30 degrees ofpronation correction. All of the guides provide a fixed additionalplantar displacement. The kit allows a surgeon to select a guidecorresponding to a left or right foot and having a desired amount of IMAcorrection. After selecting the appropriate guide, the surgeon may thenselect the amount of pronation correction by choosing the correspondingsaw slot. The tray may include other items useful in the osteotomyprocedure such as fixation pins 464.

FIGS. 63-65 illustrate an osteotomy procedure using the kit 450. FIG. 63is a dorsal view of the first and second rays 470, 472 of a right foothaving an IMA of approximately 19 degrees. A guide 456 is selected fromthe kit 450 corresponding to a 9 degree IMA correction. The guide 456 ismounted on the metatarsus 474 with the bottom of the guide 456 restingon the longitudinal axis 420 of the guide, the longitudinal axis 420parallel to the metatarsal longitudinal axis, the plane containing thefixation hole axes 426, 424 aligned parallel to the sagittal plane, andthe proximal end aligned with the MTC joint. In the illustrative exampleof FIGS. 63-65, the surgeon selects the saw slot corresponding to a 10degree pronation correction and uses it to guide a saw blade 476 to forma cut 478 defining a rotation plane 479 between proximal and distalportions 480, 482 of the metatarsus.

In FIG. 65, the distal portion of the metatarsus along with thephalanges 484, 486 have been rotated within the plane 479 defined by thecut 478 to reduce the IMA by 9 degrees as well as correct the pronationby 10 degrees and produce a compensating plantar displacement of themetatarsal head. If desired, the surgeon may fine tune the position ofthe distal portion of the first ray by sliding the cut surfaces inaddition to rotating them. The osteotomy may be fixed using pins,screws, plates, or other devices and methods as is known in the art.

Various illustrative examples of devices and methods of producing amulti-planar osteotomy on a bone have been provided. Examples of guideshave been provided that can be used to define a rotation axis and/orcorresponding rotation plane in three rotational degrees of freedomrelative to a bone to perform a tri-planar rotational osteotomy. Whilesuch a guide may be used to perform a tri-planar rotational osteotomy onany bone, it has been illustrated for example to produce a tri-planarrotational osteotomy on a first metatarsus of a human foot to correctangular alignment of the first ray of the foot. The illustrativeexamples are particularly useful to a surgeon inasmuch as they providethe surgeon with the ability to intraoperatively select at least one ofthe correction angles. For example, an exemplary guide has beendisclosed that allows the surgeon to vary the value of one of the threeangular degrees of freedom simply by choosing one of a plurality ofguiding features such as a hole defining a rotation axis or a surface orslot defining a rotation plane. An exemplary guide has been disclosedthat allows the surgeon to vary the value of two of the three angulardegrees of freedom by selecting one of a plurality of guiding featuresarranged in a matrix. Sets of guides have been disclosed that allow thesurgeon to intraoperatively vary a third angular degree of freedom. Ithas been shown that the angular degrees of freedom may be stated interms of rotational degrees or as displacements if additionalinformation is provided regarding the size and shape of the bone and thelocation of the osteotomy. Examples have been disclosed in which theangular degrees of freedom may be related to a metatarsus of a foot sothat they correspond to, for example, IMA, pronation, and plantarflexion. Guides have been disclosed that may be configured to allow userselectability of any one of IMA, pronation, and plantar flexion. Guideshave been disclosed that may be configured to allow user selectabilityof any two of IMA, pronation, and plantar flexion. Guides have beendisclosed as sets of guides that may be configured to allow userselectability of IMA, pronation, and plantar flexion. Guides have beendisclosed having a plurality of cutter guiding features differing in theamount of angular correction. It is within the scope of the invention toprovide a single cutter guiding feature with an adjustable position topermit varying the value of one or more angular corrections. It will beunderstood that substitutions among the various examples and variationsare within the scope of the invention. For example, more or feweroptions with regard to correction angles may be provided, alternativefixation of the guide to the bone may be incorporated, and differentcorrections may be coupled on a particular guide. For example, aparticular guide may have a fixed pronation correction and variable IMAcorrection or a particular guide or set of guides may have variableplantar displacement. Many combinations are possible and the presentinventors have demonstrated multiple, but not a comprehensive listingof, examples illustrating some of the possible combinations of featureswithin the scope of the invention.

What is claimed is:
 1. An osteotomy system operable to guide theformation of a tri-planar rotational osteotomy between a proximalportion of a metatarsal bone and a distal portion of the metatarsalbone, the tri-planar rotational osteotomy being operable to establish anorientation between the proximal and distal portions of the metatarsalbone incorporating coupled changes in at least two of theintermetatarsal angle, pronation, and plantar flexion of the distalportion of the metatarsal bone, the osteotomy system comprising: atleast one cutter guide comprising: reference features operable to alignthe cutter guide with the metatarsal bone in a predetermined position;and one or more cutter guiding features each defining an osteotomy planeor rotation axis relative to the metatarsal bone and corresponding to acoupled change in at least two of intermetatarsal angle, pronation, andplantar flexion of the distal portion of the metatarsal bone, at leastone of the change in intermetatarsal angle, pronation, and plantarflexion being user selectable among a plurality of values at the time ofsurgery; and a cutter operable to selectively reference one of the oneor more cutter guiding features to cut the metatarsal bone to mobilizethe proximal portion of the metatarsal bone and the distal portion ofthe metatarsal bone relative to one another and produce cut surfaces onwhich the distal portion of the metatarsal bone and the proximal portionof the metatarsal bone are relatively rotatable.
 2. The osteotomy systemof claim 1 wherein the one or more cutter guiding features comprises aplurality of cutter guiding features in which each of the plurality ofcutter guiding features defines an osteotomy plane or rotation axisdiffering from that of another cutter guiding feature in at least one ofthe amount of change in intermetatarsal angle, pronation, and plantarflexion.
 3. The osteotomy system of claim 1 wherein at least two of thechange in intermetatarsal angle, pronation, and plantar flexion are userselectable among a plurality of values at the time of surgery.
 4. Theosteotomy system of claim 1 wherein the at least one cutter guidecomprises a set of cutter guides in which each member of the set ofcutter guides is operable to permit at least one of the change inintermetatarsal angle, pronation, and plantar flexion to be userselectable among a plurality of values at the time of surgery andwherein each member of the set of cutter guides has a fixed value for atleast one of the change in intermetatarsal angle, pronation, and plantarflexion that is different from that of another member of the set ofcutter guides.
 5. The osteotomy system of claim 1 wherein the one ormore cutter guiding features comprises a plurality of saw blade guidingsurfaces.
 6. The osteotomy system of claim 5 wherein the plurality ofsaw blade guiding surfaces comprises a plurality of saw slots.
 7. Theosteotomy system of claim 6 wherein the at least one cutter guidecomprises a plurality of cutter guides, each guide having a plurality ofslots in which each slot within that particular guide corresponds to adifferent osteotomy plane producing the same change in intermetatarsalangle but a different change in pronation, the change in intermetatarsalangle produced by the slots of each guide differing from the change inintermetatarsal angle produced by the slots of another guide.
 8. Theosteotomy system of claim 7 wherein each slot in the plurality of slotsof each guide produces a change in plantar displacement of the distalend of the metatarsal bone that is the same as each other slot.
 9. Theosteotomy system of claim 8 wherein the change in plantar displacementof the distal end of the metatarsal bone is the same for all guides inthe set of guides.
 10. The osteotomy system of claim 6 wherein the atleast one cutter guide comprises a plurality of cutter guides, eachguide having a plurality of slots in which each slot within thatparticular guide corresponds to a different osteotomy plane producingthe same change in pronation but a different change in intermetatarsalangle, the change in pronation produced by the slots of each guidediffering from the change in pronation produced by the slots of anotherguide.
 11. A method of performing an osteotomy on a metatarsal bonehaving a proximal portion and a distal portion, the proximal and distalportions defining a first relative position between them, the methodcomprising: determining a desired positional change between the proximalportion of the metatarsal bone and the distal portion of the metatarsalbone in at least two anatomic reference planes; mounting a guide on themetatarsal bone; establishing an osteotomy plane or rotational axis withthe guide; guiding a cutter in the osteotomy plane or about therotational axis to mobilize the proximal portion of the metatarsal boneand the distal portion of the metatarsal bone relative to one anotherand produce cut surfaces on which the distal portion of the metatarsalbone and proximal portion of the metatarsal bone are relativelyrotatable, the cut surfaces being oriented to incorporate the desiredpositional change in the at least two anatomic reference planes;rotating the distal portion of the metatarsal bone relative to theproximal portion of the metatarsal bone to a second relative positiondifferent from the first relative position; and fixing the distalportion of the metatarsal bone and the proximal portion of themetatarsal bone relative to one another in the second relative positionwith the cut surfaces of the proximal portion of the metatarsal bone andthe distal portion of the metatarsal bone abutting one another.
 12. Themethod of claim 11 wherein: determining a desired positional changebetween the proximal portion of the metatarsal bone and distal portionof the metatarsal bone in at least two anatomic reference planescomprises determining a desired positional change between the proximalportion of the metatarsal bone and the distal portion of the metatarsalbone in three anatomic reference planes; and establishing an osteotomyplane or rotational axis with the guide comprises placing a pin in themetatarsal bone, the pin having a longitudinal axis coincident with adesired rotational axis.
 13. The method of claim 12 wherein the cutteris engaged with the pin for rotation about the pin.
 14. The method ofclaim 12 wherein: the cutter is a saw blade, the method furthercomprising engaging a saw guide with the pin, the saw guide defining aplane normal to the rotational axis, and guiding the saw blade in theplane defined by the saw guide; and guiding a saw blade comprises:guiding the saw blade to cut the metatarsal bone under the pin;advancing the pin so that it engages the proximal portion of themetatarsal bone and the distal portion of the metatarsal bone onopposite sides of the plane defined by the saw guide; and continuing thecut to complete mobilizing the distal portion of the metatarsal bonerelative to the proximal portion of the metatarsal bone, whereinrotating the distal portion of the metatarsal bone relative to theproximal portion of the metatarsal bone comprises rotating the distalportion of the metatarsal bone about the pin.
 15. The method of claim 11wherein mounting a guide on the metatarsal bone comprises: placing theguide on the metatarsal bone; aligning the guide relative to a firstanatomic plane to constrain two rotational degrees of freedom; andaligning the guide relative to an anatomic landmark to constrain a thirdrotational degree of freedom.
 16. The method of claim 15 comprisingaligning a portion of the guide with a joint between the metatarsal boneand an adjacent bone.
 17. The method of claim 15 wherein aligning theguide relative to a first anatomic plane comprises aligning the guide inthe sagittal plane and wherein aligning the guide relative to ananatomic landmark comprises aligning the guide relative to alongitudinal anatomic axis of the metatarsus.
 18. The method of claim 11wherein determining a desired positional change between the proximalportion of the metatarsal bone and the distal portion of the metatarsalbone in at least two anatomic reference planes comprises determining adesired angular change in an intermetatarsal angle and a desired angularchange in a pronation angle.
 19. The method of claim 11 wherein: theguide includes a plurality of saw guiding features, each saw guidingfeature corresponding to an osteotomy plane incorporating a differentpositional change in at least two of intermetatarsal angle, pronation,and plantar flexion, the method further comprising selecting one of theplurality of saw guiding features, and guiding a saw blade in thecorresponding osteotomy plane; the plurality of saw guiding featurescomprise a plurality of slots, each slot configured to produce a uniquecombination of change in intermetatarsal angle and pronation; and theguide is provided as a plurality of guides, each guide having aplurality of slots in which each slot produces the same change inintermetatarsal angle but a different change in pronation, the change inintermetatarsal angle produced by each guide differing from the changein intermetatarsal angle produced by each other guide.
 20. An osteotomysystem operable to guide the formation of a tri-planar rotationalosteotomy between a proximal portion of a metatarsal bone and a distalportion of the metatarsal bone, the osteotomy system comprising: atleast one cutter guide comprising: reference features operable to alignthe cutter guide with the metatarsal bone in a predetermined position;and at least two cutter guiding features each defining an osteotomyplane or rotation axis relative to the metatarsal bone and correspondingto a coupled change in at least two of intermetatarsal angle, pronation,and plantar flexion of the distal portion of the metatarsal bone, the atleast two cutter guiding features defining osteotomy planes that areangled relative to one another in at least two rotational degrees offreedom; and a cutter operable to selectively reference one of the atleast two cutter guiding features to cut the metatarsal bone to mobilizethe proximal portion of the metatarsal bone and the distal portion ofthe metatarsal bone relative to one another and produce cut surfaces onwhich the distal portion of the metatarsal bone and the proximal portionof the metatarsal bone are relatively rotatable.